1. Field of the Invention
The present invention relates to a planar microprobe, more particularly to a planar microprobe integrated with an electrostatic actuator and is realized by sacrificial layer technology and microelectroforming technology.
2. Description of the Related Art
The appearance of microprobes mainly has two kinds. One is the so-called "cubic probe", whose tip is protruded from the plane of the cantilever beam. Another is the so-called "planar probe", whose tip is coplanar with the cantilever beam. The probe of this invention is the type of the planar probe. The cubic probe including an electrostatic actuator was previously used to drive the probe to move in the direction perpendicular to the surface of the cantilever beam. The electrostatic actuator of the cubic probe is made by bonding two silicon wafers which are used as an upper cantilever beam and a lower cantilever beam. The above-mentioned cubic probe is disclosed in "Microlever with Combined Integrated Sensor/Actuator Functions for Scanning Force Microscopy," Sensors and Actuators, A, 43 (1994) pp. 339-345, by J. Brugger, N. Blanc, Ph. Renaud and N. F. de Rooij. The prior art cubic probe has several drawbacks as follows:
(1) The diameter of the tip of the cubic probe is more than 10 nm, but the diameter of the tip of the planar microprobe can reach 1 nm.
(2) Because of the uneasy alignment between the upper cantilever beam and lower cantilever beam, external voltage control will lose its accuracy if a misalignment occurs.
(3) Because the thicknesses of the two silicon wafers are not easy to control, the thicknesses and rigidities of the products produced in batches are not fixed, and thus the operating characteristic will fluctuate.
(4) The electrode plate is made of a heavily doped silicon wafer. The wafer has larger resistance. Accordingly, the problems of power-consumption and difficult heat-dissipation occur.